I had a similar decision between 3880 and 4800 to make, and opted for the 3880, mainly because of office real estate considerations, and final price, after including shipment of the very heavy 4800 to my extremely remote place (which all big companies are happy to use as an excuse to ask for outrages, 2-3... times higher prices than in the US). In addition to everything already mentioned, it is also simply the newer technology. Would I have had the choice though, I would have bought the Canon 5100 for the vacuum, internal profiling, higher ink capacity, 11 inks, and better archival inks. Only it was also more expensive here than the 3880, which was on special offer at the time.
That said, I am very happy with my 3880 under heavy usage for color prints. One thing though made my wife ask me, how they dare to sell a printer that makes all kind wheel and other horizontal marks. It's less visible than with the 3800 (now you have to carefully inspect, but at the price I am asking for the prints, my costumers do that), and good varnishing helps a great deal, but still I didn't know what to answer to her, except my usual great socio-economical rant...